Apparatus for heating synthetic filaments

ABSTRACT

An apparatus for heating a great number of synthetic filaments or a tow uniformly and with good thermal efficiency in a slittype heater while having them run in and out of the slit by disposing a plurality of buffer plates in the slit to obstruct outside air flowing into the slit with the running filaments, and thereby prevent a drop of air temperature in the slit, and make possible a substantially constant air temperature transversely of the slit.

United States Patent lnventors Kinyu lshida;

Yasuhiro Okamura, Ehime-ken, Japan Appl. No. 843,004 Filed July 18, 1969Patented Feb. 2, 1971 Assignee Teijin Limited Osaka, Japan Priority July23, 1968 Japan 43/51966 APPARATUS FOR HEATING SYNTHETIC FILAMENTS 5Claims, 5 Drawing Figs.

11.5. CI 263/3, 28/62, 57/34, 219/388, 219/524 Int. Cl F27b 9/28 Fieldof Search 219/388, 536, 537, 524; 34/152; 263/3; 57/341-1; 264/290;28/62H [56] References Cited UNITED STATES PATENTS 1,656,709 1/1928Kelly 219/388 2,624,934 1/1953 Munson et a1. 28/62X 2,877,332 3/1959Senior, Jr. 219/536 3,319,047 5/1967 Jones, Jr. et al. 219/388 3,349,22210/1967 Johnston 219/388 3,387,833 6/1968 Whittaker et al. 263/33,444,357 5/1969 Drugmand 219/535 Primary Examiner-Volodymyr Y. MayewskyAttorney-Wenderoth, Lind and Ponack ABSTRACT: An apparatus for heating agreat number of synthetic filaments or a tow uniformly and with goodthermal efficiency in a slit-type heater while having them run in andout of the slit by disposing a plurality of buffer plates in the slit toobstruct outside air flowing into the slit with the running filaments,and thereby prevent a drop of air temperature in the slit, and makepossible a substantially constant air temperature transversely of theslit.

PATENTEU FEB 21% EDGE CENTER E1565 POSITION (P) INVENTORS KINYU ISHIDAand YASUHIRO OKAMURA y APPARATUS FOR HEATING SYNTHETIC FILAMENTS Theinstant invention relates to an apparatus for heating syntheticfilaments or a tow for their heat-drawing and heattreatment.

Further, the invention relates to a slit-type heating apparatus whereina great number of running synthetic filaments or a tow are less apt tobe given inconsistent mechanical properties such as fiber strength, heatshrinkage, etc., because air temperature drop is prevented andconsistent heating is provided in the slit-type heating apparatus.

After the extrusion from spinnerets, synthetic filaments are generallyheat-drawn to several times their original lengths with a feed rollrunning at a specified peripheral speed and a draw roll running severaltimes as fast as the feed roll and are then heat treated. As a heatingapparatus ,for the heat-drawing and heat-treatment of such syntheticfilaments, there have heretofore been used such devices as a steamheater, an infrared ray heater, a fluidized bed heater, a hot-aircirculation system, a heating member contact system, etc. Among them, aso-called slit-type heater wherein filaments are advanced in a narrowpassage excels the others in the ease of operations, the simplicity ofthe equipment, and absence of fiber damage due to friction, said slitbeing formed by having a pair of heating plates facing each other.

However, the disadvantage of this slit-type heater is that cold airaccompanying a large number of running filaments is introduced throughthe entrance into the inside of the slit and thereby the temperaturewithin the slit of the heating apparatus falls, resulting in thelowering of heating efficiency. Then this is followed by aninconsistency of the temperature within the apparatus.

It has been found that there is a difference between the I heating ofthe filaments running through the center of the slit and those runningthrough the ends, with undesirable results such as variations instrength and elongation, heat shrinkage, etc.

In order that the above disadvantage may be eliminated, the instantinvention has been made. A plurality of buffer plates are installed inthe slit; the air accompanying the running filaments is thereby blockedand diverted, and consequently the temperature differences in thelateral direction of the slit have successfully been decreased.

It is the object of the instant invention to prevent cold air fromflowing from the entrance into the slit of a slit-type heating apparatusaccompanying a number of the running filaments and to thereby preventthe lowering of thermal efficiency.

It is a further object of the instant invention to eliminate theinconsistency of air temperatures in the slit-type heater and to heatthe whole of the running filaments uniformly.

One embodiment of the instant invention will be described with referenceto the accompanying drawings in which:

FIG. 1 is a perspective view of a slit-type heating apparatus accordingto the instant invention in the opened state;

FIGS. 2a2c are vertical sections showing various types of buffer plateslocated inside the slit; and

FIG. 3 is a heat distribution diagram showing heat distribution measuredtransversely of the slit.

Test results of measuring temperature with a number of thermocouplesdisposed transversely of slit-type heaters are shown in FIG. 3. In thedrawing, the abscissa (P) denotes the positions of the measurement,which extend transversely of the interior of the heater from one side tothe other across the center, and the ordinate (C.) denotes the measuredtemperature. The plotting of the test results for a conventionalslit-type heater is shown in curve A. It is seen that there is a drop intemperature in the center of the slit.

Referring to FIG. 1, the slit-type heater of this invention comprises anupper heating plate 1 and a lower heating plate 2; shallow grooves 3 and3' are provided in the central surfaces of heating plates 1 and 2 facingeach other, and a slit is defined by grooves 3 and 3' when heatingplates 1 and 2 are put together; a number within filaments run along thespace of the slit and are subjected to heating. In heating plates 1 and2,

heating elements, for instance, electric resistors 6 and 6' may beembedded as shown in the drawing, or hollow spaces may be provided inthe interior of the plates 1 and 2 to permit steam or other heatingfluids flow through them. It is desired that the space formed by grooves3 and 3' be as narrow as possible, for the narrowness helps preventoutside air having lower temperatures from flowing into the slit.However, while a number of filaments 5 are running into the slit,outside air enters the slit, accompanying the filaments. The amount ofoutside air entering is intense in the center of the slit and somewhatgentle at both ends. In FIG. 3 showing heating distribution, the heatingat the center is less than at the ends. This is because a greater amountof outside air having a lower temperature than the temperature withinthe slit enters the center of the slit and the temperature there dropsto a greater extent. In order that the fault may be corrected, aplurality of buffer plates are placed in the slit formed with grooves 3and 3' as shown in FIG. I. Said buffer plates may be mounted on upperheating plate I only or on the lower heating plate 2 only. It isdesirable to secure the buffer plates so that they are almost at rightangles to the running filaments 5, but this does not mean that they mustbe positioned as such a right angle. Buffer plates 4 and filaments S arepreferably closely adjacent each other, but contact between them shouldbe avoided because the filaments may be damaged by friction. The greaterthe number of bufier plates, the better will be the effect.

The buffer plates may be mounted in both grooves 3 and 3 alternately, incorresponding positions, or irregularly. FIGS. 20-20 are verticalsectional side views of slit-type heaters provided with various types ofbuffer plates. FIG. 2 a shows heater having I-shaped plates, FIG. 2b aheater having T- shaped plates, and FIG. 2c a heater having L-shapedplates. FIG. 3 shows heat distribution measured transversely of the slitat positions cm. from the entrance, when a slit-type heater having aslit being 2 m. long, 20 cm. wide, 3 cm. high was heated to 340 C. andI0 polyethylene terephthalate drawn yarns of 2,000 denier eachpositioned parallel to each other and at equal intervals were advancedat a speed of 250 m./min. Curve A denotes the case when buffer plates 4were not provided, and the center of the slit has very low heatingtemperatures as compared with the ends of the slit. This is because nearthe center greater amounts of outside air accompany the runningfilaments and flow into the slit. On the other hand, curve B shows theheat distribution in the same slit-type heater wherein 20 I-shapedbufler plates as shown in FIG. 2 were mounted on the upper and the lowerheating plate respectively at equal intervals and alternately.

It was found that with this apparatus thermal efficiency was enhancedand the unevenness of temperature transversely of the slit disappeared.

When the buffer plates were not employed, there was 2.8 percentdifference in shrinkage percentage at the boil between filaments at theends of the slit and those in the center, but there was only 0.3 percentwhen buffer plates were employed.

As stated above, according to the instant invention, outside air havinga temperature is prevented from flowing into the heater, and therebythermal efficiency can be enhanced, and further because variations inheating in the lateral direction of the slit are eliminated, filamentscan be heated uniformly. Thus conventional slit-type heaters have beenremarkably improved.

We claim:

I. A slit-type heater for heating synthetic filaments comprising a pairof opposed heating plates of heat conductive material, each having agroove along the face thereof facing toward the other heating plate, thegrooves together defining an elongated slit when the heating plates areagainst one another, a heating means in each heating plate for heatingthe heating plate, and a plurality of buffer plates positioned at spacedintervals along the groove in each heating plate and extending from thebottom of the groove in a direction out of the groove substantiallyperpendicular to said groove and from one side to the other side of saidgroove and terminating sufficiently short of the surface of the heatingplate which is to abut the surface of the other heating plate to providea space between the buffer plates sufficiently large to allow thefilaments to run through the slit without contacting the buffer plates,whereby the temperature transversely of the slit is made substantiallyuniform by the action of the buffer plates in preventing outside airfrom being drawn into the slit by the movement of the filaments throughthe slit.

2. A slit-type heater as claimed in claim 1 in which said buffer platesin one heater plate are offset in the direction of the length of theslit from the buffer plates in the other heater plate.

3. A slit-type heater as claimed in claim I in which said buffer platesare l-shaped in cross section.

4. A slit-type heater as claimed in claim 1 in which said buffer platesare T-shaped in cross section with the crossbar portion thereof adjacentthe other heater plate.

5. A slit-type heater as claimed in claim 1 in which said buffer platesare L-shaped in cross section with the transverse portion thereofadjacent the other heater plate.

2. A slit-type heater as claimed in claim 1 in which said buffer platesin one heater plate are offset in the direction of the length of theslit from the buffer plates in the other heater plate.
 3. A slit-typeheater as claimed in claim 1 in which said buffer plates are I-shaped incross section.
 4. A slit-type heater as claimed in claim 1 in which saidbuffer plates are T-shaped in cross section with the crossbar portionthereof adjacent the other heater plate.
 5. A slit-type heater asclaimed in claim 1 in which said buffer plates are L-shaped in crosssection with the transverse portion thereof adjacent the other heaterplate.